Stacked microfeature devices and associated methods

ABSTRACT

Stacked microfeature devices and associated methods of manufacture are disclosed. A package in accordance with one embodiment includes first and second microfeature devices having corresponding first and second bond pad surfaces that face toward each other. First bond pads can be positioned at least proximate to the first bond pad surface and second bond pads can be positioned at least proximate to the second bond pad surface. A package connection site can provide electrical communication between the first microfeature device and components external to the package. A wirebond can be coupled between at least one of the first bond pads and the package connection site, and an electrically conductive link can be coupled between the first microfeature device and at least one of the second bond pads of the second microfeature device. Accordingly, the first microfeature device can form a portion of an electrical link to the second microfeature device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/104,862, filed Aug. 17, 2018, now U.S. Pat. No. 11,373,979, which isa continuation of U.S. application Ser. No. 15/368,158, filed Dec. 2,2016, now U.S. Pat. No. 10,062,667; which is a continuation of U.S.application Ser. No. 13/845,953, filed Mar. 18, 2013, now U.S. Pat. No.9,515,046; which is a divisional of U.S. application Ser. No.12/820,704, filed Jun. 22, 2010, now U.S. Pat. No. 8,400,780; which is adivisional of U.S. application Ser. No. 11/416,740, filed May 3, 2006,now U.S. Pat. No. 7,742,313; which is a continuation of U.S. applicationSer. No. 10/651,912, filed Aug. 29, 2003, now U.S. Pat. No. 7,071,421;each of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention is directed generally to stacked microfeaturedevices and methods for manufacturing such packages.

BACKGROUND

One method for increasing the density of microelectronic circuits forelectronic devices (such as computers, portable phones, etc.) is tostack two or more microelectronic dies on top of each other.Accordingly, this arrangement can provide additional circuits within thesame footprint normally occupied by a single die. FIG. 1 is a partiallyschematic, cross-sectional elevational view of an existing stacked diepackage 10. The package 10 includes a substrate 40 that carries a firstdie 20 and a stacked second die 30. The first die 20 is attached to thesubstrate 40 with a paste layer 14. A spacer 12 is attached to the firstdie 20 with a first tape layer 13 a. The second die 30 is attached tothe spacer 12 with a second tape layer 13 b.

The first die 20 includes first die bond pads 21 that are coupled tocorresponding first substrate bond pads 41 a with first wirebonds 50 a.The first substrate bond pads 41 a are coupled to external substratebond pads 41 c with vias. The external substrate bond pads 41 c eachhave a substrate solder ball 42 to provide communication between thefirst die 20 and devices located external to the package 10. Similarly,the second die 30 includes second die bond pads 31 coupled tocorresponding second substrate bond pads 41 b with second wirebonds 50b. The second substrate bond pads 41 b are coupled to additionalexternal substrate bond pads 41 c to provide communication between thesecond die 30 and devices external to the package. Once the first andsecond wirebonds 50 a, 50 b are connected, the substrate 40, the firstdie 20, and the second die 30 can be at least partially enclosed with anencapsulant 12 to protect these components.

One feature of an arrangement shown in FIG. 1 is that the overallthickness of the package 10 can be significantly greater than thecombined thicknesses of the substrate 40, the first die 20, and thesecond die 30. As a result, the package 10 can be difficult to integrateinto devices having very tight vertical clearances. Accordingly, thebenefits of the stacked die arrangement provided to the standard sizedevices in which they are incorporated may not be available for verycompact devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially schematic, cross-sectional elevation view of apackage having stacked microelectronic dies in accordance with the priorart.

FIG. 2 is a partially schematic, cross-sectional elevation view of apackage having dies stacked and coupled in accordance with an embodimentof the invention.

FIG. 3 is a partially schematic, partially exploded isometric view oftwo dies positioned to be stacked in accordance with another embodimentof the invention.

FIG. 4 is a partially schematic, partially exploded view of two diespositioned to be stacked in accordance with yet another embodiment ofthe invention.

FIG. 5 is a partially schematic, partially exploded view of two dieshaving off-center bond pads and being positioned to be stacked inaccordance with still another embodiment to the invention.

DETAILED DESCRIPTION A. Introduction

The present invention is directed to stacked microfeature devices andassociated methods. The term “microfeature device” is used throughout toinclude a device formed from a substrate upon which and/or in whichsubmicron circuits or components and/or data storage elements or layersare fabricated. Submicron features in the substrate include, but are notlimited to, trenches, vias, lines, and holes. These features typicallyhave a submicron width (e.g., ranging from, for example, 0.1 micron to0.75 micron) generally transverse to a major surface (e.g., a front sideor a back side) of the device. The term microfeature device is also usedto include substrates upon which and/or in which micromechanicalfeatures are formed. Such features include read/write head features andother micromechanical features having submicron or supermicrondimensions. In many of these embodiments, the substrate is formed fromsuitable materials, including ceramics, and may support layers and/orother formations of other materials, including but not limited tometals, dielectric materials and photoresists.

A microfeature device package in accordance with one aspect of theinvention can include a first microfeature device having a plurality offirst bond pads at least proximate to a first bond pad surface, and asecond microfeature device having a plurality of second bond pads atleast proximate to a second bond pad surface. The second bond padsurface can face toward the first bond pad surface. A package connectionsite can be positioned to provide electrical communication between thefirst microfeature device and components external to the device package.A wirebond can be coupled between at least one of the first bond padsand the package connection site, and an electrically conductive link canbe coupled between the first microfeature device and at least one of thesecond bond pads of the second microfeature device.

In a particular aspect of the invention, the wirebond is one of aplurality of wirebonds and all the wirebonds of the package areconnected directly to the first microfeature device. In a furtherparticular aspect of the invention, the first microfeature deviceincludes an intermediate bond pad electrically coupled to the at leastone first bond pad, and the electrically conductive link is connectedbetween the intermediate bond pad and the at least one second bond padof the second microfeature device. In yet another aspect of theinvention, the first microfeature device includes an intermediate bondpad electrically isolated from the at least one first bond pad, and theelectrically conductive link is connected between the intermediate bondpad and the at least one second bond pad of the second microfeaturedevice.

The present invention is also directed towards methods for forming amicrofeature device package. In one aspect of the invention, the methodincludes positioning a first microfeature device at least proximate to asecond microfeature device, with the first microfeature device having afirst bond pad surface with a plurality of first bond pads at leastproximate to the first bond pad surface, and with the secondmicrofeature device having a second bond pad surface with a plurality ofsecond bond pads at least proximate to the second bond pad surface. Thefirst bond pad surface can be positioned to face toward the second bondpad surface. A wire bond can be coupled between at least one of thefirst bond pads and a package connection site that is positioned toprovide electrical communication between the first microfeature deviceand components external to the device package. An electricallyconductive link can be coupled between the first microfeature device andat least one of the second bond pads of the second microfeature device.

In a particular aspect of the invention, the wire bond is one of aplurality of wire bonds and the method further includes connecting allthe wire bonds of the package directly to the first microfeature device.In other aspects of the invention, the first microfeature device caninclude an intermediate bond pad electrically coupled to the at leastone first bond pad, and coupling an electrically conductive link betweenthe first microfeature device and the at least one second bond pad caninclude coupling the electrically conductive link between theintermediate bond pad and the at least one second bond pad. In yetanother aspect of the invention, the intermediate bond pad iselectrically isolated from the at least one first bond pad.

B. Methods and Apparatuses in Accordance with Embodiments of theInvention

Several specific details of the invention are set forth in the followingdescription and in FIGS. 2-5 to provide a thorough understanding ofcertain embodiments of the invention. One skilled in the art, however,will understand that the present invention may have additionalembodiments, and that other embodiments of the invention may bepracticed without several of the specific features explained in thefollowing description.

FIG. 2 is a partially schematic, cross-sectional illustration of apackage 110 having a first microfeature device 120 and a secondmicrofeature device 130 stacked in accordance with an embodiment of theinvention. In one aspect of this embodiment, all the wirebonds withinthe package 110 can be attached directly to the first microfeaturedevice 120, with some wirebonds communicating only with the firstmicrofeature device 120, and with others communicating only with thesecond microfeature device 130, via additional electrical linkspositioned between the first microfeature device 120 and the secondmicrofeature device 130. In another embodiment, at least some of thewirebonds can be coupled to both the first microfeature device 120 andthe second microfeature device 130. In both embodiments, the firstmicrofeature device 120 can provide a platform that supports electricallinks coupled to the second microfeature device 130. As described ingreater detail below, this arrangement can reduce the overall thicknessof the package 110 by eliminating wirebonds connected directly to thesecond microfeature device 130.

In one aspect of an embodiment shown in FIG. 2 , the package 110includes a support member 140, for example, a printed circuit board. Thesupport member 140 can carry the first and second devices 120, 130 andcan provide for electrical communication between these devices, as wellas devices or circuits external to the package 110. Accordingly, thesupport member 140 can have a plurality of package connection sites 143,shown in FIG. 2 as first package connection sites 143 a and secondpackage connection sites 143 b offset forward of the first packageconnection sites 143 a. Each of the package connection sites 143 caninclude a package connector 142 to provide for communication withelements external to the package 110. In one embodiment, the packageconnectors 142 include solder balls and in other embodiments, thepackage connectors 142 include other electrically conductive structures.In any of these embodiments, the first package connection sites 143 acan be coupled to first support member bond pads 141 a with a vias thatextend through the support member 140. The second package connectionsites 143 b can be coupled to corresponding second support member bondpads 141 b, also with vias that extend through the support member 140.The first support member bond pads 141 a and the second support memberbond pads 141 b are connected to the first microfeature device 120 andthe second microfeature device 130, respectively, as described ingreater detail below.

In one aspect of an embodiment shown in FIG. 2 , the first microfeaturedevice 120 can be attached to the support member 140 with a paste layer114. In other embodiments, the first microfeature device 120 can beattached to the support member 140 with other arrangements. In any ofthese embodiments, the first microfeature device 120 can include firstdevice bond pads 121 that are electrically coupled to features locatedwithin the first microfeature device 120. The first device bond pads 121can be connected to the first support member bond pads 141 a with firstwirebonds 150 a. In a particular aspect of this embodiment, each of thefirst wirebonds 150 a can be attached to a stud bump (e.g., a gold studbump) or other feature located at the corresponding first device bondpad 121 to improve the physical and/or electrical characteristics of theconnection between the wirebond 150 a and the first device bond pad 121.In other embodiments, the first wirebond 150 a can be attached directlyto the first device bond pad 121. In still a further aspect of thisembodiment, the first wirebond 150 a can be attached first to thesupport member 140 and then to the first microfeature device 120, forexample, to reduce the extent of the wirebond loop.

The first microfeature device 120 can also carry intermediate bond pads122. In one aspect of this embodiment, some or all of the intermediatebond pads 122 are not electrically connected to features within thefirst microfeature device 120, but instead, provide an intermediatepoint in an electrical communication link between the secondmicrofeature device 130 and the support member 140. In anotherembodiment, at least some of the intermediate bond pads 122 areelectrically connected to corresponding first device bond pads 122(e.g., via a redistribution layer) or directly to features within thefirst microfeature device 120. In another embodiment, the intermediatebond pads 122 can be connected to the second substrate bond pads 141 bwith second wirebonds 150 b. As described in greater detail below, thesecond microfeature device 130 can also be electrically coupled to theintermediate bond pads 122 to complete the communication link betweenthe second package connection sites 143 b located at the support member140, and the features within the second microfeature device 130.

The second microfeature device 130 can include second bond pads 131 thatare electrically connected to features within the second microfeaturedevice 130. In one aspect of an embodiment shown in FIG. 2 , the secondbond pads 131 may not be aligned directly above the intermediate bondpads 122 located on the first microfeature device 120. Accordingly, thesecond microfeature device 130 can include auxiliary bond pads 132 whichare aligned with the intermediate bond pads 122. The auxiliary bond pads132 can be connected to the second bond pads 131 with couplers 134. Inone embodiment, the couplers 134 are part of a redistribution layer, andin other embodiments, the couplers 134 have other arrangements. In oneaspect of an embodiment shown in FIG. 2 , the coupling between theauxiliary bond pads 132 and the second bond pads 131 can be at thesurface of the second microfeature device 130. In other embodiments, theconnection between the bond pads 131, 132 can be located within theinterior of the second microfeature device 130. In any of theseembodiments, the auxiliary bond pad 132 can be connected to anelectrically conductive member 133 that is aligned with a correspondingone of the intermediate bond pads 122 on the first microfeature device120 below. In one embodiment, the electrically conductive member 133includes a stud bump, (e.g., a gold stud bump, a copper stud bump or asolder bump) and in other embodiments, the electrically conductivemember 133 includes other structures. In any of these embodiments, theelectrically conductive member 133 can be physically and electricallybonded to the intermediate bond pad 122 and/or to the portion of thesecond wirebond 150 b attached to the intermediate bond pad 122.

In a particular aspect of an embodiment shown in FIG. 2 , the package110 is subjected to ultrasonic energy and/or an elevated temperature tosecure the connection between the auxiliary bond pad 132 and theintermediate bond pad 122. In other embodiments, other techniques areused to secure this connection. In any of these embodiments, theconnection between the auxiliary bond pad 132 and the intermediate bondpad 122 can both physically secure the second microfeature device 130 tothe first microfeature device 120, and can provide electricalcommunication between the second device bond pad 131 and the secondpackage connection site 143 b. Once this connection is complete, anoptional encapsulant 111 can be disposed over the support member 140,the first microfeature device 120 and the second microfeature device 130to protect these components. In one embodiment, the encapsulant 111 caninclude a no-sweep encapsulant, available from KNS of Willow Grove,Pennsylvania. In other embodiments, the encapsulant 111 can includeother products.

One feature of an embodiment of the package 110 described above withreference to FIG. 2 is that the second wirebonds 150 b need not extendaround the outwardly facing edges 160 of the second microfeature device130. Instead, the second wirebonds 150 b attach to the intermediate bondpads 122 of the first microfeature device 120, with the electricallyconductive member 133 providing the link to the second microfeaturedevice 130. One advantage of this feature is that the overall thicknessT of the package 110 can be reduced when compared with existing packagesbecause the encapsulant 111 need not extend beyond the secondmicrofeature device 130 by an amount necessary to envelope the secondwirebond 150 b. Instead, the second wirebond 150 b is positioned betweenthe first microfeature device 120 and the second microfeature device130. Because the resulting package 110 is accordingly thinner thanconventional structural die packages, it can more easily be installed inlocations that require a low profile device.

Another advantage of the foregoing arrangement is that the encapsulant111 need not envelop the entire second microfeature device 130. Forexample, if the second microfeature device 130 includes a first surface135 a and a second, oppositely facing surface 135 b, the second surface135 b need not be covered with the encapsulant 111. As a result the rateat which heat is transferred from the second microfeature device 130 canbe enhanced, due to the exposed second surface 135 b.

Another feature of an embodiment of the package 110 described above withreference to FIG. 2 is that the package 110 can have package outer edges115 that are located more closely to the device outer edges 160 of thesecond microfeature device 130 than are the outer edges of existingpackages. In particular, because the second wirebonds 150 b need notextend around the device outer edges 160, the package outer edges 115can be flush with the device outer edges 160, or can extend only a shortdistance outwardly from the device outer edges 160. Accordingly, theoverall width W of the package 110 can also be reduced when comparedwith existing packages and the package 110 can accordingly be moreeasily installed in locations having tight lateral space constraints.

Still another feature of an embodiment of the package 110 describedabove with reference to FIG. 2 is that all the wirebonds of the package110 can be connected to the first microfeature device 120 and noneconnected to the second microfeature device 130. Accordingly, all thewirebonds of the package 110 can be connected in a single pass, e.g.,the package 110 need not undergo two separate wirebonding procedures,one for the first microfeature device 120 and another for the secondmicrofeature device 130. An advantage of this arrangement is that it canreduce the time and cost associated with producing the package 110.

In other embodiments, the package 110 can have other configurations. Forexample, the first and second microfeature devices 120, 130 can havegenerally similar shapes and configurations, with the second device bondpads 131 arranged in a mirror image of the first device bond pads 121.Signals dedicated to either the first or second microfeature device canbe routed via arrangements generally similar to those described belowwith reference to FIG. 5 . In still further embodiments, the package 110can include more than two microfeature devices. For example, in oneembodiment, third or third and fourth microfeature devices can bestacked on the second microfeature device 130, with separate wirebondsrouted to the third microfeature device.

FIG. 3 is a partially exploded, partially schematic isometricillustration of a package 310 that includes a support member 340, afirst microfeature device 320, and a stacked second microfeature device330 arranged in accordance with another embodiment of the invention. Inone aspect of this embodiment, the first microfeature device 320 hasfeatures arranged in exactly the same manner as the correspondingfeatures of the second microfeature device 330. Accordingly, anymicrofeature device having this arrangement can be stacked upon anyother microfeature device having the same arrangement. In other words,the microfeature device at the bottom of the stack need not have adifferent configuration than the microfeature device attached above.

In one aspect of an embodiment shown in FIG. 3 , the first microfeaturedevice 320 can have a first bond pad surface 325, with first device bondpads 321 positioned at least proximate to the first bond pad surface325. For purposes of illustration, the first device bond pads 321 shownin FIG. 3 are labeled with numerals 1-8. Each first device bond pad 321can be coupled to a first wirebond pad 328 with a corresponding firstcoupler 327. The first couplers 327 can include metal lines or otherconductive structures located at or proximate to the first bond padsurface 325. In one aspect of this embodiment, the first device bondpads 321 are aligned with a device centerline 324 passing through thecenter of the first microfeature device 320. In other embodiments, thefirst device bond pads 321 can be located off the device centerline 324,as described in greater detail below with reference to FIG. 5 .

As described above, the second microfeature device 330 can have featuresarranged generally similarly to those of the first microfeature device320. Accordingly, the second microfeature device 330 can include asecond bond pad surface 335, second device bond pads 331 (also labeledwith numerals 1-8) at least proximate to the second bond pad surface335, and second wirebond pads 338 coupled to the second device bond pads331 with second couplers 337. The first and second microfeature devices320, 330 can be stacked in a face-to-face arrangement on the supportmember 340, as described in greater detail below.

In one aspect of an embodiment shown in FIG. 3 , the support member 340includes package connection sites 343, for example, bond pads that areaccessible from the outside of the package 310. Package connectors 342(e.g., solder balls or other electrically conductive elements) can becoupled to the package connection sites 343 to provide for electricalcommunication with components outside the package 310. The packageconnection sites 343 can be electrically coupled to the first wirebondpads 328 with wirebonds 350. Accordingly, the wirebonds 350 can transmitsignals between the package connection sites 343 and the first bond pads321.

In a particular aspect of an embodiment shown in FIG. 3 , signalstransmitted to and from the first device bond pads 321 of the firstmicrofeature device 320 are also transmitted to and from thecorresponding second device bond pads 331 of the second microfeaturedevice 330. Accordingly, when the second microfeature device 330 isstacked face down on top of the first microfeature device 320, each ofthe numbered second bond pads 331 aligns with the same correspondinglynumbered first bond pad 321 of the first microfeature device 320. Thesecond device bond pads 331 can be electrically connected to thecorresponding first device bond pads 321 with electrically conductivemembers 323, initially disposed on the first bond pads 321. In oneembodiment, the electrically conductive members 323 include solderballs, and in other embodiments, the electrically conductive members 323include other structures. In any of these embodiments, the entireassembly can then be encapsulated with an encapsulant 111 (a smallportion of which is shown in FIG. 3 ) in a manner generally similar tothat shown in FIG. 2 .

FIG. 4 illustrates a partially exploded isometric view of a package 410configured in accordance with another embodiment to the invention. Inone aspect of this embodiment, the package 410 includes first and secondmicrofeature devices 420, 430 having at least generally similar layouts,stacked face-to-face on a support member 440. Accordingly, the firstmicrofeature device 420 can include a first bond pad surface 425 on ornear which are positioned first bond device pads 421 (labeled withnumerals 1-8) coupled to first wirebond pads 428 with first couplers427. In one aspect of this embodiment, each first device bond pad 421 iscoupled to a pair of first wirebond pads 428 with a coupler 427 thatextends laterally to the left and right of the centrally positionedfirst device bond pad 421. Wirebonds 450 connect the wirebond pads 428to package connection sites 443. In one aspect of this embodiment, halfthe wirebonds 450 connect to the first wirebond pads 428 located to theright of the first bond pads 421, and half connect to the first wirebondpads 428 located to the left of the first bond pads 421. In otherembodiments, the wirebonds 450 are distributed in other manners.

Microfeature devices having the foregoing arrangement can be positionedon the bottom of the stack (e.g., in the position of the firstmicrofeature device 420) or, by rotating the microfeature device andplacing it face down, on the top of the stack (e.g., in the position ofthe second microfeature device 430). The second microfeature device 430includes a second bond pad surface 435 that carries second device bondpads 431 electrically coupled to second wirebond pads 438 with secondcouplers 437. Those second wirebond pads 438 that are aligned with thewirebonds 450 below can include electrically conductive members 433(e.g., solder balls) that physically couple the second microfeaturedevice 430 to the first microfeature device 420, and electrically couplethe second device bond pads 431 to the corresponding first device bondpads 421. Accordingly, signals transmitted to and/or received by thefirst device bond pads 421 are also transmitted to and/or received bythe second bond pads 431.

FIG. 5 is a partially exploded, isometric view of a package 510configured to provide communication links to a first microfeature device520 and separate communication links to a stacked second microfeaturedevice 530. In one aspect of this embodiment, the first microfeaturedevice 520 includes ten active first device bond pads 521 (shown asfirst device bond pads 521 a-521 j) positioned along a first axis 570that is offset from a centerline 526 of the first microfeature device520. The first microfeature device 520 can also include correspondingfirst intermediate bond pads 522 (shown as first intermediate bond pads522 a, 522 c-522 j) that are aligned (with the exception of firstintermediate bond pad 522 g) along a second axis 571. The second axis571 is mirrored relative to the first axis 570 about the centerline 526.The first device bond pads 521 can be connected to first wirebond pads528 with couplers 527. Wirebonds 550 can electrically couple the firstwirebond pads 528 (and therefore, the first bond pads 521) to a supportmember 540.

The second microfeature device 530 can have a layout identical to thatof the first microfeature device 520, with ten active second device bondpads 531 a-531 j aligned along a first axis 580, and correspondingsecond intermediate bond pads 532 a-532 j generally aligned along asecond axis 581. The first axis 580 and the second axis 581 can beequidistant from a centerline 536 of the second microfeature device 530.Accordingly, when the second microfeature device 530 is positioned abovethe first microfeature device 520, it is rotated so that the seconddevice bond pads 531 align with the correspondingly numbered firstintermediate bond pads 522, and the second intermediate bond pads 532align with the correspondingly numbered first device bond pads 521.

Some signals transmitted to/from the package 510 are shared by the firstmicrofeature device 520 and the second microfeature device 530 and areaccordingly transmitted via both the first device bond pads 521 and thecorrespondingly numbered second device bond pads 531. For example,signals transmitted via the first device bond pads 521 a-e, i and j arealso transmitted via the corresponding second device bond pads 531 a-e,i and j, respectively. Accordingly, the couplers 527 for these bond padsconnect these bond pads to the correspondingly numbered intermediatebond pads 522, 532 mirrored across the device centerlines 526, 536.Electrically conductive members 533 (e.g., solder balls) disposed on thefirst intermediate bond pads 522 electrically connect the first bondpads 521 of the first microfeature device 520 to the correspondingsecond bond pads 531 of the second microfeature device 530. For example,signals transmitted to/from the first device bond pad 521 a are alsotransmitted to/from the second device bond pad 531 a via an electricallyconductive member 533 disposed between the first intermediate bond pad522 a and the second device bond pad 531 a.

Other signals transmitted to/from the package 510 are transmittedto/from only the first microfeature device 520 and/or only the secondmicrofeature device 530. For example, signals transmitted via the firstdevice bond pads 521 f and 521 h of the first microfeature device 520are independent of signals transmitted via the second device bond pads531 f and 531 h of the second microfeature device 530. Accordingly, thefirst device bond pad 521 f is not electrically coupled to itscorresponding first intermediate bond pad 522 f, but instead has anindependent coupler 527 f 1 connected to a wirebond 550 f 1 at a firstwirebond pad 528 f 1. The first intermediate bond pad 522 f has aseparate coupler 527 f 2 connected at a corresponding first wirebond pad528 f 2 to wirebond 550 f 2. An electrically conductive member 533 atthe first intermediate bond pad 522 f electrically couples the wirebond550 f 2 to the second device bond pad 531 f of the second microfeaturedevice 530. Accordingly, signals transmitted via the first device bondpad 521 f are transmitted independently of signals transmitted via thesecond device bond pad 531 f.

A generally similar though more complex arrangement is used to transmitsignals via the first bond pad 521 h independently of signalstransmitted via the second bond pad 531 h. The first bond pad 521 h iscoupled with a coupler 527 h 1 to a corresponding wirebond pad 528 h 1and a corresponding wirebond 550 h 1. Accordingly, signals travelto/from the first device bond pad 521 h directly via the coupler 527 h 1and the wirebond 550 h 1.

A separate and electrically isolated coupler 527 h 2 is connectedbetween a first intermediate bond pad 522 h 2 and a wirebond pad 528 h2, which is coupled to a wirebond 550 h 2. The first intermediate bondpad 522 h 2 is positioned on a third axis 572. Additional firstintermediate bond pads 522 h 3, 522 h and 522 h 4 are electricallyconnected to each other and are positioned on the centerline 526, thesecond axis 571, and a fourth axis 573, respectively. The fourth axis573 mirrors the third axis 572 about the centerline 526. Electricallyconductive members 533 are disposed on the intermediate bond pads 522 h2, 522 h 3 and 522 h. Corresponding second intermediate bond pads 532 h2, 532 h, 532 h 3 and 532 h 4 on the second microfeature device arepositioned to route electrical signals between the second device bondpad 531 h and the wirebond 550 h 2, as follows: When the secondmicrofeature device 530 is positioned face down on the firstmicrofeature device 520 and physically and electrically coupled to it,signals travel to/from the second device bond pad 531 h along a paththat includes the wirebond 550 h 2, the coupler 527 h 2, the firstintermediate bond pad 522 h 2, then to the corresponding secondintermediate bond pad 532 h 4 (of the second microfeature device 530),then to the second intermediate bond 532 h 3 (of the second microfeaturedevice 530) then to the corresponding first intermediate bond pad 522 h3 (of the first microfeature device 520) then to the first intermediatebond pad 522 h and finally to the second bond pad 531 h of the secondmicrofeature device 530.

One feature of an arrangement of microfeature devices described abovewith reference to FIG. 5 is that signals can be transmitted to/from someor all of the bond pads 521 of the first microfeature device 520independently of signals transmitted to/from the corresponding bond pads531 of the second microfeature device 530. This feature can increase theversatility of the package 510 because some or all aspects of themicrofeature devices 520, 530 can be independently controlled despitethe fact that they are stacked in the same package 510.

Another feature of the microfeature devices 520, 530 described abovewith reference to FIG. 5 is that both the first microfeature device 520and the second microfeature device 530 can have identical featurelayouts. Accordingly, even though each microfeature device 520, 530 isconfigured to receive separate signals when combined in the package 510,the devices themselves need not be manufactured to differentspecifications. An advantage of this arrangement is that costsassociated with manufacturing and/or inventorying separate microfeaturedevices suitable for stacked packaging can be avoided, reducing theoverall cost of the package 510. Another advantage of this arrangementis that the likelihood for inadvertently connecting the microfeaturedevices in an incorrect manner can be reduced because the microfeaturedevices can have identical layouts.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thespirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

We claim:
 1. A microfeature device assembly, comprising: a first diehaving a first bond pad surface, wherein the first bond pad surfaceincludes a plurality of first device bond pads aligned along a firstaxis, a plurality of first intermediate bond pads aligned along a secondaxis, and a plurality of wirebond pads, wherein: a first subset of theplurality of wirebond pads are electrically coupled to a correspondingpair from the plurality of first device bond pads and the plurality offirst intermediate bond pads, a second subset of the plurality ofwirebond pads are each electrically coupled to an individual one of theplurality of first device bond pads, and a third subset of the pluralityof wirebond pads are each electrically coupled to an individual one ofthe plurality of first intermediate device bond pads; a second diecarried by the first die and having a second bond pad surface facing thefirst bond pad surface, wherein the second bond pad surface includes aplurality of second device bond pads each vertically aligned with acorresponding one of the plurality of first intermediate bond pads alongthe second axis and a plurality of second intermediate bond pads eachvertically aligned with a corresponding one of the plurality of firstdevice bond pads along the first axis; and a conductive member disposedon each of the plurality of first intermediate bond pads andindividually coupling the plurality of first intermediate bond pads tothe plurality of second device bond pads.
 2. The microfeature deviceassembly of claim 1 wherein signals arriving at the first subset of theplurality of wirebond pads are communicated to each of the first die andthe second die.
 3. The microfeature device assembly of claim 1 whereinsignals arriving at the second subset of the plurality of wirebond padsare communicated only to the first die, and wherein signals arriving atthe third subset of the plurality of wirebond pads are communicated onlyto the second die.
 4. The microfeature device assembly of claim 1,further comprising: a support member carrying the first die; and awirebond coupling each of the plurality of wirebond pads to the supportmember.
 5. The microfeature device assembly of claim 1 wherein the firstbond pad surface has a centerline, and wherein the first axis and thesecond axis are equidistant from the centerline.
 6. The microfeaturedevice assembly of claim 1 wherein the second bond pad surface has anidentical feature layout to the first bond pad surface.
 7. Themicrofeature device assembly of claim 1 wherein: the first bond padsurface further includes a third intermediate bond pad on a third axis,wherein the third axis is further from a centerline of the first bondpad surface than the second axis; and the second bond pad surfacefurther includes a fourth intermediate bond pad vertically aligned withthe third intermediate bond pad on the third axis.
 8. The microfeaturedevice assembly of claim 1 wherein: the first bond pad surface furtherincludes a third intermediate bond pad positioned along a centerline ofthe first bond pad surface; and the second bond pad surface furtherincludes a fourth intermediate bond pad vertically aligned with thethird intermediate bond pad.
 9. The microfeature device assembly ofclaim 1 wherein each of the conductive members comprises a volume ofsolder material.
 10. The microfeature device assembly of claim 1 whereinat least one of the plurality of first intermediate bond pads iselectrically coupled to a corresponding wirebond pad through the secondbond pad surface.
 11. A microfeature device assembly, comprising: asupport member; a first die carried by the support member and having afirst active surface, wherein: the first active surface includes a firstset of bond pads having two or more first device bond pads aligned alonga first axis, two or more first intermediate bond pads aligned along asecond axis parallel to the first axis, and three or more wirebond padspositioned peripheral to the first axis and the second axis, and thefirst set of bond pads includes a subset of bond pads electricallycoupled to one of the three or more wirebond pads via a coupler at thefirst active surface, the subset of bond pads comprising a correspondingpair from the two or more first device bond pads and the two or morefirst intermediate bond pads; a second die carried by the first die andhaving a second active surface, wherein the second active surfaceincludes a second set of bond pads, the second set of bond pads havingtwo or more second device bond pads each vertically aligned with acorresponding one of the two or more first intermediate bond pads; and aconductive structure electrically coupling each of the two or moresecond device bond pads to the corresponding one of the two or morefirst intermediate bond pads.
 12. The microfeature device assembly ofclaim 11 wherein the subset of bond pads is a first subset, wherein theone of the three or more wirebond pads is a first wirebond pad, andwherein the first set of bond pads further includes: a second subsetelectrically coupled to a second one of the three or more wirebond pads,the second subset including an independent one of the two or more firstdevice bond pads; and a third subset electrically coupled to a third oneof the three or more wirebond pads, the third subset including anindependent one of the two or more first intermediate bond pads.
 13. Themicrofeature device assembly of claim 11 wherein the first axis and thesecond axis are equidistant from a centerline of the first die.
 14. Themicrofeature device assembly of claim 11 wherein the two or more firstintermediate bond pads are arranged along the second axis in a mirrorimage about a centerline of the first die relative to the two or morefirst device bond pads along the first axis.
 15. The microfeature deviceassembly of claim 11 wherein each of the three or more wirebond pads arepositioned adjacent to a perimeter of the first active surface.
 16. Themicrofeature device assembly of claim 11, further comprising three ormore wirebonds individually coupling each of the three or more wirebondpads to the support member.
 17. A stacked microfeature device assembly,comprising: a support member; and two dies carried by the supportmember, each of the two dies having an active surface that includes aplurality of device bond pads and a plurality of intermediate bond pads,wherein: on a first die of the two dies: the plurality of device bondpads are aligned along a first axis; the plurality of intermediate bondpads are aligned along a second axis; and at least one pair of bond padsfrom the plurality of device bond pads and the plurality of intermediatebond pads are jointly coupled to a first wirebond pad at the activesurface; on a second die of the two dies: the plurality of device bondpads are aligned along the second axis and independently verticallyaligned with a corresponding one of the plurality of intermediate bondpads on the first die; and the plurality of intermediate bond pads arealigned along the second axis and independently vertically aligned witha corresponding one of the plurality of device bond pads on the firstdie; and each of the plurality of device bond pads on the second dieelectrically coupled to the corresponding one of the pluralityintermediate bond pads on the first die.
 18. The stacked microfeaturedevice assembly of claim 17 wherein, on the first die: at least one ofthe plurality of device bond pads is independently coupled to a secondwirebond pad at the active surface; and at least one of the plurality ofintermediate bond pads is independently coupled to a third wirebond padat the active surface.
 19. The stacked microfeature device assembly ofclaim 17 wherein the active surface of each of the two dies has anidentical arrangement of the plurality of device bond pads and theplurality of intermediate bond pads.
 20. The stacked microfeature deviceassembly of claim 17 wherein the first die includes at least oneintermediate bond pad electrically coupled to a wiredbond pad through atleast one intermediate bond pad on the second die.